Semiconductor chips often require a shield for protection against electromagnetic interference. Shielding from electromagnetic interference is required especially for many radio frequency applications.
One way is to use the semiconductor substrate beneath the active device or structure for shielding in chip scale packages. However, this approach may not be suitable since there may be strong electromagnetic interference or since the active device or structure may be very sensitive to electromagnetic interference.
Another way is to form a metal cover at the printed circuit board (PCB) level over the devices. The metal cover may be formed for instance by spray coating with conductive ink (on a carbon base or a silver base) or by physical vapor deposition.
FIGS. 1A to 1D show a method of forming a package such as a ball grid array. FIG. 1A is a schematic 100a showing a cross sectional view of semiconductor chips 102 being arranged on a substrate 104 which may include a routing structure. The routing structure may include multiple layers of metallization 104a separated from one another by dielectric layers 104b. Molding material 106 may be deposited onto the semiconductor chips 102. FIG. 1B is a schematic 100b showing a cross sectional view of the structure formed in FIG. 1A being pre-diced. Dicing trenches 108 may be formed to expose a portion of the metallization 104a (e.g. the ground contacts). FIG. 1C is a schematic 100c showing a cross sectional view of the structure formed in FIG. 1B being coated with a shielding layer 110. FIG. 1D is a schematic 100d showing a cross sectional view of the structure formed in FIG. 1C being singulated to form a plurality of package arrangements 112.